Pathology studies the causes and effects of diseases. It addresses various components of a disease, like pathogenesis, morphologic changes and clinical manifestations. In general medical practice, it is focused on analyzing clinical abnormalities which are precursors and markers for infectious and non-infectious diseases. Pathology can be categorized into anatomical pathology and clinical pathology. Anatomical pathology diagnoses the diseases on the basis of molecular, gross, immunologic, microscopic and chemical examination of tissues, organs or whole bodies. Various subfields of anatomical pathology include forensic pathology, surgical pathology and cytopathology. Clinical pathology is involved in the diagnosis of diseases on the basis of laboratory analysis of tissues and body fluids like urine and blood, with the help of tools of molecular pathology, chemistry, hematology and clinical microbiology. Pathology work like blood tests, biopsy and resection are necessary for diagnosing various kinds of cancers. Similarly, blood and tissue analysis is important for the investigation of infectious diseases. This book explores all the important aspects of pathology in the present day scenario. It will help the readers in keeping pace with the rapid changes in this field.